The basic neurobiology and potential clinical utilization of neuron specific enolase (NSE) has been a long-standing interest in our laboratory. During the past year, studies have begun to focus on the molecular biology of NSE in an effort to use the brain enolase isoenzyme system as a model to study neuron specific gene expression. We now have cDNA probes for both NSE and non- neuronal enolase (NNE). The probes have been characterized and in situ hybridization studies have been performed in human brain. Our cDNA probe for NSE only labels neurons whereas the probe for NNE preferentially labels glial cells. Studies performed using northern blots in both rat and guinea pig brain reveal that the mRNA for NSE is substantially larger than that for NNE. There is approximately a 75% homology within the coding region for human NNE and NSE (some 1700 base pairs). The 3'non-coding region is much larger for NSE and has very little homology to that of NNE, a fact we made use of to generate specific probes. Studies are in progress regarding the NNE to NSE switch that occurs during neural differentiation. Studies are also in progress to determine the effect of cerebral ischemia on brain NSE levels in gerbil brain. In these studies we will attempt to demonstrate that NSE levels can be used as an index of neural damage post ischemia. The effect of various protective agents such as adenosine receptor agonists will also be assessed. Clinical studies assessing NSE levels in both human CSF and serum consequent to stroke are also in progress. The goal here is to determine whether NSE levels are correlated with the degree of post-ischemic neurologic damage.